Sliding seal and valve for reciprocating pump



. Oct. 6, 1970 1.. F; HERRESHOFF' 3,532,446

. SLIDING SEAL AND VALVE FOR RECIPROCATINGPUMP Filed April 4. 1967 2Sheets-Sheet -L3 INVENTOB ATTORNEY Oct. 6, 1970 3,532,446

SLIDING SEAL AND VALVE FOR RECIPROCATING PUMP Filed April 4, 1967 L. F.HERRESHOFF 2 Sheets-Sheet 1 ie-Ju L Mk5 lNVE NTOR I 1 n: E ELL- ATTORNEYUnited States Patent O US. Cl. 417-511 9 Claims ABSTRACT OF THEDISCLOSURE A pump for liquids including a substantial cylindrical barreland a reciprocating pump piston located in the barrel and havingcombined sealing and check valve means comprising an annulus ofresilient material in peripheral sliding engagement with the interior ofthe barrel and a piston cage loosely confining the annulus for limitedaxial movement relative to the cage, and in which the annulus has across-section forming a flexible ridge engaging the inner surface of thebarrel so that differences in the diameter of the inner surface may becompensated by twisting the ridge.

CROSS-REFERENCE TO RELATED APPLICATION The present application is acontinuation-in-part application of the application Ser. No. 435,307filed by the same inventor with the same title on Feb. 25, 1965, and nowPat. No. 3,319,577.

BACKGROUND OF THE INVENTION The present invention relates to pumps andmore particularly to reciprocating pumps such as hand operated bilgepumps for boats. The invention is concerned with improvements in theplunger or piston of such pumps and especially with the improvementresiding in the sealing ring of the plunger.

In conventional types of simple reciprocating pumps, such as employedfor pumping out the bilge of a boat, the piston or plunger which isreciprocated within the pump barrel may employ a cup-shaped element ofleather or resilient material to provide a sliding seal between plungerand barrel. In some instances, this cup-shaped element may also serve asa valve, with the walls of the cup yielding inwardly on the downwardstroke to enable liquid to flow upwardly between the cup and the barrel.On the upstroke, the walls of the cup, under the weight of liquid above,move outwardly into contact with the barrel to provide a sliding seal.Alternatively, there may be included within the pump plunger a separatecheck valve which opens on the down stroke and closes on the upstroke,leaving the cup-shaped member to function solely as a sliding sealbetween piston and barrel.

In either of these commonly employed arrangements, there is considerabledifficulty due to clogging. Foreign matter is apt to become caughtbetween sealing surfaces and the sliding seal or in the check valve,requiring that the pump be dismantled and cleaned or temporarilyoperated at reduced efiiciency and later cleaned.

It is an object of the present invention to overcome these difficultiesconnected with plunger pumps of the aforementioned kind and to provide apump plunger or piston of novel construction and configuration, whereina combined sliding seal and check valve is employed in a manner thatprovides a relatively large flow capacity and is substantially free fromclogging by foreign matter.

Another difficulty residing in manufacturing pumps of the aforementionedkind is to' provide for a proper sliding seal regardless of smallvariations in the diameter of the pump barrel which may especially occurin mass fabrication of pumps of this type, especially when the pumpbarrel is formed by an extruded plastic tube.

It is especially an object of the present invention to provide for asliding seal which is constructed and arranged to automaticallycompensate for small variations in the diameter of the pump barrel.

SUMMARY OF THE INVENTION With these objects in view, the presentinvention is directed on the one hand to a pump for liquids including asubstantially cylindrical barrel, a reciprocated plunger rod member inthe barrel, a pump piston fixed to the rod member and having combinedsealing and check valve means comprising an annulus of resilientmaterial in peripheral sliding engagement with the interior of the pumpbarrel, and a piston cage loosely confining the annulus for limitedaxial movement relative to the cage, the cage including an annular stop,a disc member against which the annulus seats on the suction stroke ofthe pump, the disc member having a diameter approximating the meandiameter of the annulus, and supporting arms secured at one end to theannular stop and at the other end to one of the aforementioned membersfor supporting the annulus in spaced relation to the disc member duringthe reverse stroke of the pump, the annulus having a cross sectionforming a flexible ridge engaging the inner surface of the barrel sothat differences in the diameter of the inner barrel surface may becompensated by twisting the ridge.

On the other hand, the present invention is directed to an article ofmanufacture in the form of an annulus of flexible material for sealinglyengaging a cylindrical surface, in which the annulus has a cross sectiontapering into a flexible ridge adapted to engage the cylindricalsurface, so that differences in the diameter of the cylindrical surfacemay be compensated by twisting the ridge.

The novel features which are considered a characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is an axial cross sectionthrough a pump according to the present invention;

FIG. 2 is a transverse cross section taken along the line 22 of FIG. 1;

FIGS. 35 schematically illustrate the engagement of the flexible annuluswith inner surfaces of pump barrels having slightly different diameters(in FIGS. 3-5 the other elements of the pump are omitted for reasons ofsimplification); and

FIGS. 6-9 are partial cross-sectional views illustrating various shapesof the cross section of the annulus drawn on an enlarged scale.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 illustrate thepresent invention embodied in a hand operated reciprocating pump of atype suitable for removing water from the bilge of a boat. The pump maycomprise a cylindrical barrel 12 having at its bottom end a centrallyopen fitting 14 which serves as the pump inlet and also provides a seatfor the check valve ball 16.

A rod 18 extends across the barrel as a retainer for the '2 a ball tolimit upward movement thereof as shown in FIG. 1.

At the top of the barrel, a bonnet 22 is provided with an outlet passagethrough sleeve 24, to which a suitable length of hose may be attached. Aplunger rod 30 extends through the bonnet into the barrel, withresilient seal ring 32 to prevent leakage. Preferably a resilient sealring 34 is also employed between the bonnet and the top end of the pumpbarrel 12. A suitable handle 36 is secured to the upper end of theplunger rod 30.

To enable the pump quickly to remove a relatively large volume of waterwith a minimum of effort on the part of the operator, a unitary pumppiston and valve structure is provided, that is distinguished by large,unobstructed flow passage on the downstroke of the pump, and effectivesealing with low friction on the lifting stroke. The pump piston fixedto the rod 30 has combined sealing and check valve means comprising asealing ring or annulus of resilient material 40 which functions both asa sliding seal and as a check valve, opening on the down stroke andclosing on the upstroke.

The pump piston comprises further a piston cage loosely confining theannulus 40 for limited axial movement relative to the cage. The cageincludes an annular stop 48, and a disc 42 against which the annulus 40seats on the upward suction stroke of the pump. The disc 42 is securedto the lower end of the rod and has a diameter substantially smallerthan the pump barrel 12, so that an annular passage of a substantialtotal area is available for fluid flow around the disc on the downstrokeof the pump. In general, the diameter of the disc may approximate themean diameter of the sealing ring or annulus 40. Preferably, the disc 42will be no larger in size than is necessary to insure that the sealingring 40 cannot slip downwardly past the disc during pumping, nor becomewedged in such a manner as to create excessive sliding friction with thepump barrel.

To take full advantage of the relatively large annular flow passagebetween the pump barrel and the periphery of the disc 42, the pistonstructure permits the resilient annulus 40 during the pumps downstroketo move axially a substantial distance away from the disc and alsopermits relative unobstructed flow through the open center of theannulus. To permit such axial movement of the annulus 40, the annularstop 48 is connected to the disc 42 by a small number, for instance 3,of independent supporting arms secured at one end to the annular stop 48and at the other end to the disc 42, which arms 48 are, as clearly shownin FIG. 2 spaced from each other a distance substantially greater thanthe width of the arms. The length of the arms is preferably such so asto permit thet sealing ring or annulus 40 to move during the pressurestroke of the pump, at which the annulus will abut against the annularstop member 48, to move away from the disc 42 far enough to provide apassage between the disc 42 and sealing ring 40 approximating the axialwidth of the sealing ring. As a consequence, the area of the passagebetween disc and seal may readily be made at least as large as the areaof the annular passage between the edge of the disc 42 and the innersurface of the pump barrel 12.

According to the present invention the cross-section of the resilientannulus 40 is not circular, but the annulus 40 has a cross-sectiontapering into a flexible ridge 50 engaging the inner surface of thebarrel 12.

Annuli or sealing rings of various cross-sections are respectively shownin FIGS. 69 which may be used in connection with the pump piston andcage above described.

The annulus 40a shown in FIG. 6 has on the side thereof facing away fromthe inner surface of the barrel 12 a substantially semicircularcross-section and is provided on the side thereof facing the innersurface of the barrel with a pair of flattened regions 52 so that thecross-section tapers from the largest diameter thereof into flexibleridge 50a which ends in a substantially sharp edge 54. The sealing rings40b and 400 respectively shown in FIGS. 7 and 8 likewise have on thesides thereof facing away from the inner surface of the barrel asubstantially semicircular cross-section and this cross-section taperstowards the inner surface of the barrel to form respectively flexibleridges 50b and 50c which have however rounded edges 56. Thecross-section of the sealing ring 400 shown in FIG. 8 is symmetricalwith respect to a plane of symmetry passing through the largest diameterof the sealing ring, whereas the cross-section of the sealing ring 4012as shown in FIG. 7 is slightly assymmetrical with regard to this planein that the ridge 50b has a substantially flat region 52 at one side anda slightly curved region 53 at the other side. The sealing ring 40dshown in FIG. 9 has a cross-section which tapers from the largest widthof the ring to opposite sides so as to form a pair of flexible ridges50c ending in rounded edges 56.

Due to the specific cross-section of the sealing ring according to thepresent invention, the sealing ring can be used with cylinders or pumpbarrels of slightly different diameters while maintaining its circularoutline so as to be in perfect sealing engagement with the inner surfaceof the pump barrel. FIG. 3 shows the arrangement of a sealing ring 40 ina pump barrel 12 having an inner diameter D which is substantially equalto the outer diameter of the sealing ring. FIG. 4 shows the same sealingring in a pump barrel having an inner diameter D which is slightlysmaller than the outer diameter of the sealing ring in unstressedcondition. In this case, when the sealing ring, when moved by engagementwith the disc 42 of the piston cage above described and not shown inFIG. 4 in the direction of the arrow indicated in FIG. 4, will twistslightly, that is the flexible ridge 50 will be deformed as shown inFIG. 4, but obviously the sealing ring will still maintain its circularoutline so as to be about its whole circumference in proper sealingengagement with the inner surface of the pump barrel. FIG. 5 shows afurther arrangement in which the inner diameter of the pump barrel D isfurther reduced and in which the flexible ridge of the sealing ring isfurther twisted so that the flat side 52 of the ridge is nearly parallelto the inner surface of the barrel. The same sealing ring may thereforebe used with barrels having diameters varying between the diameter D andD In manufacturing the pump barrel and the sealing ring cooperatingtherewith it will be advantageous to manufacture the inner diameter ofthe barrel to a theoretical value slightly smaller than the outerdiameter of the sealing ring in unstressed condition so as to obtain aproper seal regardless whether the manufacturing tolerances of the innerdiameter of the barrel are on the plus or on the minus side. Thespecific cross-section of the sealing ring will be especiallyadvantageous when the barrel is made by extruding a plastic tube, sincein extruding plastic material it is very difficult to maintain extremelyclose tolerances.

The operation of the pump above described will be obvious from thedescription thereof. On the upward stroke, the parts are as shown inFIG. 1 with the sealing ring 40 in engagement with the disc 42 toprovide a substantially fluid tight sliding piston and the upward or suction stroke of which serves to draw water into the pump barrel past theopen check valve at the bottom. At the reversal of the sroke, the ball16 drops to close the check valve at the inlet and prevents the escapeof water from the barrel. As the pump rod starts its downward movement,the piston cage lowers freely through the sealing ring which tends toremain stationary with respect to the pump barrel until engaged by thestop 48 of the cage. Upon continued downward movement of the piston, thesealing ring 40 will be carried along by the annular stop 48 with thewater below the piston flowing freely around the disc 42 then inwardlybetween the disc and the sealing ring and upwardly through the sealingring into the open region above the piston. With the next upward strokeof the pump, the water above the piston is ejected through the dischargespout 24, while the barrel below the piston is filling, as before.

By reason of the relatively open structure of the piston cage and thelarge area of the flow passages provided, the pump has little tendencyto clog. Should any chip or other foreign matter likely to be present inthe bilge water get caught between the sealing ring 40' and the disc 42at the beginning of an upstroke, such obstruction will almost always beflushed free by the rush of water through the piston as soon as thecheck valve opens on the following downstroke.

The flow passages of the pump are so substantial in area and so freefrom obstructions that the pump, when used as a bilge pump for boats, isnot only much easier to operate than co'nventional pumps of comparablebarrel size but is notably free from clogging. By the specificconstruction of the cross-section of the sealing ring, the sealingaction of the latter is improved as compared with sealing rings ofcircular cross-section, and the manufacturing of the pump is facilitatedin that the sealing ring according to the present invention will providea proper seal without the necessity of maintaining the inner surface ofthe barrel at close tolerances.

7 It will be understood that each of the elements described above, ortwo or more together, may also find a useful application in other typesof pumps differing from the types described above.

Evidently, the sealing ring according to the present invention may alsobe used not only in pumps but in other arrangements in which a properseal has to be provided on a cylindrical surface.

What is claimed is:

1. A pump for liquids, comprising in combination, a substantiallycylindrical barrel; a reciprocable plunger rod member in said barrel;and a pump piston fixed to said rod member and having combined sealingand check valve means comprising an annulus of resilient material inperipheral sliding engagement with the inner surface of said pumpbarrel, and a piston cage loosely confining said annulus for limitedaxial movement relative to said cage, said cage including an annularstop, a disc member against which said annulus seats on the suctionstroke of the pump, the disc member having an outer diameterapproximating the mean diameter of said annulus, and supporting armssecured at one end to said annular stop and at the other end to one ofsaid members for supporting said annulus in spaced relatio'n to saiddisc member during the reverse stroke of the pump, said annulus having across-section forming a flexible ridge engaging the inner surface ofsaid barrel so that differences in the diameter of said inner surfacemay be compensated by twisting said ridge.

2. A pump as defined in claim 1, wherein said crosssection of saidannulus tapers into a flexible ridge engaging the inner surface of saidbarrel.

3. A pump as defined in claim 2, wherein said crosssection of saidannulus is substantially semicircular on the side thereof facing awayfrom said inner surface and tapers from the largest diameter of saidcross-section into a flexible ridge engaging the inner surface of saidbarrel.

4. A pump as defined in claim 3, wherein said ridge has a rounded edge.

5. A pump as defined in claim 3, wherein said ridge has a substantiallysharp edge.

6. A pump according to claim 1, wherein said annulus has a cross-sectiontapering into a flexible ridge engaging said inner surface of saidbarrel so that differences.

in the diameter of said inner surface may be compensated for by twistingsaid ridge and said annulus having opposite said flexible ridge arounded surface.

7. A pump according to claim 1, wherein the flexible ridge of saidannulus has a rounded edge.

8. A pump according to claim 1, wherein said flexible ridge of saidannulus has a substantially sharp edge.

9. A pump according to claim 1, wherein said annulus has a cross-sectiontapering from tis largest width to opposite sides into flexible ridges.

References Cited UNITED STATES PATENTS 2,360,085 10/1944 Thompson103-178 X 2,444,119 6/1948 Thor'n et al. 277-177 2,783,068 2/1957 Bloomet al. 277-177 FOREIGN PATENTS 1,354,369 1/1964 France. 1,147,898 4/1963 Germany.

928,876 6/ 1963 Great Britain.

417,250 1/ 1967 Switzerland.

LAVERNE D. GEIGER, Primary Examiner I. S. MEDNICK, Assistant ExaminerU.S. Cl. X.R. 277-173, 177, 207

